Integrated SequencePhysics Chemistry Organic Biology

Web Resources

  click if a link is broken

Special points of emphasis


The Prokaryotic Cell

The Eukaryotic Cell

Gene Expression

The Digestive System and Nutrition

In both prokaryotes and eukaryotes, newly synthesized proteins contain signals determining their ultimate destination. In eukaryotes, the presence of a particular kind of signal sequence in the protein determines that the ribosome not remain free in the cytosol during translation but is directed to the endoplasmic reticulum. Signal sequences are typically on the order of approximately twenty residues in length. They are cleaved from the rest of the protein within the lumen of the ER. Such proteins synthesized on the endoplasmic reticulum become bound in the lumen of the ER, entering the endomembrane system, including eventually the Golgi complex, for modification, sorting, and delivery. Secretory and membrane proteins are synthesized on the rough ER.

Cells specialized for the manufacture of secretory proteins, such as the cells within the pancreas that produce digestive enzymes, contain large quantities of rough ER.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

Please read our policies on privacy and shipping & returns.  Contact Us.
MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course.

Creative Commons License
The work of WikiPremed is published under a Creative Commons Attribution Share Alike 3.0 License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions. You can use the resources here for commercial or non-commercial purposes, but please give attribution and a link to the production credits and edit history of the resource. For the works here which began as my individual work, please attribute "John Wetzel, an author at".